/*
** $Id: loadlib.c,v 1.52.1.4 2009/09/09 13:17:16 roberto Exp $
** Dynamic library loader for Lua
** See Copyright Notice in lua.h
**
** This module contains an implementation of loadlib for Unix systems
** that have dlfcn, an implementation for Darwin (Mac OS X), an
** implementation for Windows, and a stub for other systems.
*/


#include <stdlib.h>
#include <string.h>


#define loadlib_c
#define LUA_LIB

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"
#include "lrotable.h"

/* prefix for open functions in C libraries */
#define LUA_POF     "luaopen_"

/* separator for open functions in C libraries */
#define LUA_OFSEP   "_"


#define LIBPREFIX   "LOADLIB: "

#define POF     LUA_POF
#define LIB_FAIL    "open"


/* error codes for ll_loadfunc */
#define ERRLIB      1
#define ERRFUNC     2

#define setprogdir(L)       ((void)0)


static void ll_unloadlib(void *lib);
static void *ll_load(lua_State *L, const char *path);
static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym);



#if defined(LUA_DL_DLOPEN)
/*
** {========================================================================
** This is an implementation of loadlib based on the dlfcn interface.
** The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,
** NetBSD, AIX 4.2, HPUX 11, and  probably most other Unix flavors, at least
** as an emulation layer on top of native functions.
** =========================================================================
*/

#include <dlfcn.h>

static void ll_unloadlib(void *lib)
{
    dlclose(lib);
}


static void *ll_load(lua_State *L, const char *path)
{
    void *lib = dlopen(path, RTLD_NOW);
    if (lib == NULL) lua_pushstring(L, dlerror());
    return lib;
}


static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
    lua_CFunction f = (lua_CFunction)dlsym(lib, sym);
    if (f == NULL) lua_pushstring(L, dlerror());
    return f;
}

/* }====================================================== */



#elif defined(LUA_DL_DLL)
/*
** {======================================================================
** This is an implementation of loadlib for Windows using native functions.
** =======================================================================
*/

#include <windows.h>


#undef setprogdir

static void setprogdir(lua_State *L)
{
    char buff[MAX_PATH + 1];
    char *lb;
    DWORD nsize = sizeof(buff) / sizeof(char);
    DWORD n = GetModuleFileNameA(NULL, buff, nsize);
    if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == NULL)
        luaL_error(L, "unable to get ModuleFileName");
    else
    {
        *lb = '\0';
        luaL_gsub(L, lua_tostring(L, -1), LUA_EXECDIR, buff);
        lua_remove(L, -2);  /* remove original string */
    }
}


static void pusherror(lua_State *L)
{
    int error = GetLastError();
    char buffer[128];
    if (FormatMessageA(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
                       NULL, error, 0, buffer, sizeof(buffer), NULL))
        lua_pushstring(L, buffer);
    else
        lua_pushfstring(L, "system error %d\n", error);
}

static void ll_unloadlib(void *lib)
{
    FreeLibrary((HINSTANCE)lib);
}


static void *ll_load(lua_State *L, const char *path)
{
    HINSTANCE lib = LoadLibraryA(path);
    if (lib == NULL) pusherror(L);
    return lib;
}


static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
    lua_CFunction f = (lua_CFunction)GetProcAddress((HINSTANCE)lib, sym);
    if (f == NULL) pusherror(L);
    return f;
}

/* }====================================================== */



#elif defined(LUA_DL_DYLD)
/*
** {======================================================================
** Native Mac OS X / Darwin Implementation
** =======================================================================
*/

#include <mach-o/dyld.h>


/* Mac appends a `_' before C function names */
#undef POF
#define POF "_" LUA_POF


static void pusherror(lua_State *L)
{
    const char *err_str;
    const char *err_file;
    NSLinkEditErrors err;
    int err_num;
    NSLinkEditError(&err, &err_num, &err_file, &err_str);
    lua_pushstring(L, err_str);
}


static const char *errorfromcode(NSObjectFileImageReturnCode ret)
{
    switch (ret)
    {
    case NSObjectFileImageInappropriateFile:
        return "file is not a bundle";
    case NSObjectFileImageArch:
        return "library is for wrong CPU type";
    case NSObjectFileImageFormat:
        return "bad format";
    case NSObjectFileImageAccess:
        return "cannot access file";
    case NSObjectFileImageFailure:
    default:
        return "unable to load library";
    }
}


static void ll_unloadlib(void *lib)
{
    NSUnLinkModule((NSModule)lib, NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES);
}


static void *ll_load(lua_State *L, const char *path)
{
    NSObjectFileImage img;
    NSObjectFileImageReturnCode ret;
    /* this would be a rare case, but prevents crashing if it happens */
    if (!_dyld_present())
    {
        lua_pushliteral(L, "dyld not present");
        return NULL;
    }
    ret = NSCreateObjectFileImageFromFile(path, &img);
    if (ret == NSObjectFileImageSuccess)
    {
        NSModule mod = NSLinkModule(img, path, NSLINKMODULE_OPTION_PRIVATE |
                                    NSLINKMODULE_OPTION_RETURN_ON_ERROR);
        NSDestroyObjectFileImage(img);
        if (mod == NULL) pusherror(L);
        return mod;
    }
    lua_pushstring(L, errorfromcode(ret));
    return NULL;
}


static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
    NSSymbol nss = NSLookupSymbolInModule((NSModule)lib, sym);
    if (nss == NULL)
    {
        lua_pushfstring(L, "symbol " LUA_QS " not found", sym);
        return NULL;
    }
    return (lua_CFunction)NSAddressOfSymbol(nss);
}

/* }====================================================== */



#else
/*
** {======================================================
** Fallback for other systems
** =======================================================
*/

#undef LIB_FAIL
#define LIB_FAIL    "absent"


#define DLMSG   "dynamic libraries not enabled; check your Lua installation"


static void ll_unloadlib(void *lib)
{
    (void)lib;  /* to avoid warnings */
}


static void *ll_load(lua_State *L, const char *path)
{
    (void)path;  /* to avoid warnings */
    lua_pushliteral(L, DLMSG);
    return NULL;
}


static lua_CFunction ll_sym(lua_State *L, void *lib, const char *sym)
{
    (void)lib;
    (void)sym;  /* to avoid warnings */
    lua_pushliteral(L, DLMSG);
    return NULL;
}

/* }====================================================== */
#endif



static void **ll_register(lua_State *L, const char *path)
{
    void **plib;
    lua_pushfstring(L, "%s%s", LIBPREFIX, path);
    lua_gettable(L, LUA_REGISTRYINDEX);  /* check library in registry? */
    if (!lua_isnil(L, -1))  /* is there an entry? */
        plib = (void **)lua_touserdata(L, -1);
    else    /* no entry yet; create one */
    {
        lua_pop(L, 1);
        plib = (void **)lua_newuserdata(L, sizeof(const void *));
        *plib = NULL;
        luaL_getmetatable(L, "_LOADLIB");
        lua_setmetatable(L, -2);
        lua_pushfstring(L, "%s%s", LIBPREFIX, path);
        lua_pushvalue(L, -2);
        lua_settable(L, LUA_REGISTRYINDEX);
    }
    return plib;
}


/*
** __gc tag method: calls library's `ll_unloadlib' function with the lib
** handle
*/
static int gctm(lua_State *L)
{
    void **lib = (void **)luaL_checkudata(L, 1, "_LOADLIB");
    if (*lib) ll_unloadlib(*lib);
    *lib = NULL;  /* mark library as closed */
    return 0;
}


static int ll_loadfunc(lua_State *L, const char *path, const char *sym)
{
    void **reg = ll_register(L, path);
    if (*reg == NULL) *reg = ll_load(L, path);
    if (*reg == NULL)
        return ERRLIB;  /* unable to load library */
    else
    {
        lua_CFunction f = ll_sym(L, *reg, sym);
        if (f == NULL)
            return ERRFUNC;  /* unable to find function */
        lua_pushcfunction(L, f);
        return 0;  /* return function */
    }
}


static int ll_loadlib(lua_State *L)
{
    const char *path = luaL_checkstring(L, 1);
    const char *init = luaL_checkstring(L, 2);
    int stat = ll_loadfunc(L, path, init);
    if (stat == 0)  /* no errors? */
        return 1;  /* return the loaded function */
    else    /* error; error message is on stack top */
    {
        lua_pushnil(L);
        lua_insert(L, -2);
        lua_pushstring(L, (stat == ERRLIB) ?  LIB_FAIL : "init");
        return 3;  /* return nil, error message, and where */
    }
}



/*
** {======================================================
** 'require' function
** =======================================================
*/


static int readable(const char *filename)
{
    FILE *f = fopen(filename, "r");  /* try to open file */
    if (f == NULL) return 0;  /* open failed */
    fclose(f);
    return 1;
}


static const char *pushnexttemplate(lua_State *L, const char *path)
{
    const char *l;
    while (*path == *LUA_PATHSEP) path++;  /* skip separators */
    if (*path == '\0') return NULL;  /* no more templates */
    l = strchr(path, *LUA_PATHSEP);  /* find next separator */
    if (l == NULL) l = path + strlen(path);
    lua_pushlstring(L, path, l - path);  /* template */
    return l;
}


static const char *findfile(lua_State *L, const char *name,
                            const char *pname)
{
    const char *path;
    name = luaL_gsub(L, name, ".", LUA_DIRSEP);
    lua_getfield(L, LUA_ENVIRONINDEX, pname);
    path = lua_tostring(L, -1);
    if (path == NULL)
        luaL_error(L, LUA_QL("package.%s") " must be a string", pname);
    lua_pushliteral(L, "");  /* error accumulator */
    while ((path = pushnexttemplate(L, path)) != NULL)
    {
        const char *filename;
        filename = luaL_gsub(L, lua_tostring(L, -1), LUA_PATH_MARK, name);
        lua_remove(L, -2);  /* remove path template */
        if (readable(filename))  /* does file exist and is readable? */
            return filename;  /* return that file name */
        lua_pushfstring(L, "\n\tno file " LUA_QS, filename);
        lua_remove(L, -2);  /* remove file name */
        lua_concat(L, 2);  /* add entry to possible error message */
    }
    return NULL;  /* not found */
}


static void loaderror(lua_State *L, const char *filename)
{
    luaL_error(L, "error loading module " LUA_QS " from file " LUA_QS ":\n\t%s",
               lua_tostring(L, 1), filename, lua_tostring(L, -1));
}


static int loader_Lua(lua_State *L)
{
    const char *filename;
    const char *name = luaL_checkstring(L, 1);
    filename = findfile(L, name, "path");
    if (filename == NULL) return 1;  /* library not found in this path */
    if (luaL_loadfile(L, filename) != 0)
        loaderror(L, filename);
    return 1;  /* library loaded successfully */
}


static const char *mkfuncname(lua_State *L, const char *modname)
{
    const char *funcname;
    const char *mark = strchr(modname, *LUA_IGMARK);
    if (mark) modname = mark + 1;
    funcname = luaL_gsub(L, modname, ".", LUA_OFSEP);
    funcname = lua_pushfstring(L, POF"%s", funcname);
    lua_remove(L, -2);  /* remove 'gsub' result */
    return funcname;
}


static int loader_C(lua_State *L)
{
    const char *funcname;
    const char *name = luaL_checkstring(L, 1);
    const char *filename = findfile(L, name, "cpath");
    if (filename == NULL) return 1;  /* library not found in this path */
    funcname = mkfuncname(L, name);
    if (ll_loadfunc(L, filename, funcname) != 0)
        loaderror(L, filename);
    return 1;  /* library loaded successfully */
}


static int loader_Croot(lua_State *L)
{
    const char *funcname;
    const char *filename;
    const char *name = luaL_checkstring(L, 1);
    const char *p = strchr(name, '.');
    int stat;
    if (p == NULL) return 0;  /* is root */
    lua_pushlstring(L, name, p - name);
    filename = findfile(L, lua_tostring(L, -1), "cpath");
    if (filename == NULL) return 1;  /* root not found */
    funcname = mkfuncname(L, name);
    if ((stat = ll_loadfunc(L, filename, funcname)) != 0)
    {
        if (stat != ERRFUNC) loaderror(L, filename);  /* real error */
        lua_pushfstring(L, "\n\tno module " LUA_QS " in file " LUA_QS,
                        name, filename);
        return 1;  /* function not found */
    }
    return 1;
}


static int loader_preload(lua_State *L)
{
    const char *name = luaL_checkstring(L, 1);
    lua_getfield(L, LUA_ENVIRONINDEX, "preload");
    if (!lua_istable(L, -1))
        luaL_error(L, LUA_QL("package.preload") " must be a table");
    lua_getfield(L, -1, name);
    if (lua_isnil(L, -1))  /* not found? */
        lua_pushfstring(L, "\n\tno field package.preload['%s']", name);
    return 1;
}


static const int sentinel_ = 0;
#define sentinel    ((void *)&sentinel_)


static int ll_require(lua_State *L)
{
    const char *name = luaL_checkstring(L, 1);
    int i;
    lua_settop(L, 1);  /* _LOADED table will be at index 2 */
    lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
    lua_getfield(L, 2, name);
    if (lua_toboolean(L, -1))    /* is it there? */
    {
        if (lua_touserdata(L, -1) == sentinel)  /* check loops */
            luaL_error(L, "loop or previous error loading module " LUA_QS, name);
        return 1;  /* package is already loaded */
    }
    /* Is this a readonly table? */
    void *res = luaR_findglobal(name, strlen(name));
    if (res)
    {
        lua_pushrotable(L, res);
        return 1;
    }
    /* else must load it; iterate over available loaders */
    lua_getfield(L, LUA_ENVIRONINDEX, "loaders");
    if (!lua_istable(L, -1))
        luaL_error(L, LUA_QL("package.loaders") " must be a table");
    lua_pushliteral(L, "");  /* error message accumulator */
    for (i = 1; ; i++)
    {
        lua_rawgeti(L, -2, i);  /* get a loader */
        if (lua_isnil(L, -1))
            luaL_error(L, "module " LUA_QS " not found:%s",
                       name, lua_tostring(L, -2));
        lua_pushstring(L, name);
        lua_call(L, 1, 1);  /* call it */
        if (lua_isfunction(L, -1))  /* did it find module? */
            break;  /* module loaded successfully */
        else if (lua_isstring(L, -1))  /* loader returned error message? */
            lua_concat(L, 2);  /* accumulate it */
        else
            lua_pop(L, 1);
    }
    lua_pushlightuserdata(L, sentinel);
    lua_setfield(L, 2, name);  /* _LOADED[name] = sentinel */
    lua_pushstring(L, name);  /* pass name as argument to module */
    lua_call(L, 1, 1);  /* run loaded module */
    if (!lua_isnil(L, -1))  /* non-nil return? */
        lua_setfield(L, 2, name);  /* _LOADED[name] = returned value */
    lua_getfield(L, 2, name);
    if (lua_touserdata(L, -1) == sentinel)     /* module did not set a value? */
    {
        lua_pushboolean(L, 1);  /* use true as result */
        lua_pushvalue(L, -1);  /* extra copy to be returned */
        lua_setfield(L, 2, name);  /* _LOADED[name] = true */
    }
    return 1;
}

/* }====================================================== */



/*
** {======================================================
** 'module' function
** =======================================================
*/


static void setfenv(lua_State *L)
{
    lua_Debug ar;
    if (lua_getstack(L, 1, &ar) == 0 ||
            lua_getinfo(L, "f", &ar) == 0 ||  /* get calling function */
            lua_iscfunction(L, -1))
        luaL_error(L, LUA_QL("module") " not called from a Lua function");
    lua_pushvalue(L, -2);
    lua_setfenv(L, -2);
    lua_pop(L, 1);
}


static void dooptions(lua_State *L, int n)
{
    int i;
    for (i = 2; i <= n; i++)
    {
        lua_pushvalue(L, i);  /* get option (a function) */
        lua_pushvalue(L, -2);  /* module */
        lua_call(L, 1, 0);
    }
}


static void modinit(lua_State *L, const char *modname)
{
    const char *dot;
    lua_pushvalue(L, -1);
    lua_setfield(L, -2, "_M");  /* module._M = module */
    lua_pushstring(L, modname);
    lua_setfield(L, -2, "_NAME");
    dot = strrchr(modname, '.');  /* look for last dot in module name */
    if (dot == NULL) dot = modname;
    else dot++;
    /* set _PACKAGE as package name (full module name minus last part) */
    lua_pushlstring(L, modname, dot - modname);
    lua_setfield(L, -2, "_PACKAGE");
}


static int ll_module(lua_State *L)
{
    const char *modname = luaL_checkstring(L, 1);
    if (luaR_findglobal(modname, strlen(modname)))
        return 0;
    int loaded = lua_gettop(L) + 1;  /* index of _LOADED table */
    lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
    lua_getfield(L, loaded, modname);  /* get _LOADED[modname] */
    if (!lua_istable(L, -1))    /* not found? */
    {
        lua_pop(L, 1);  /* remove previous result */
        /* try global variable (and create one if it does not exist) */
        if (luaL_findtable(L, LUA_GLOBALSINDEX, modname, 1) != NULL)
            return luaL_error(L, "name conflict for module " LUA_QS, modname);
        lua_pushvalue(L, -1);
        lua_setfield(L, loaded, modname);  /* _LOADED[modname] = new table */
    }
    /* check whether table already has a _NAME field */
    lua_getfield(L, -1, "_NAME");
    if (!lua_isnil(L, -1))  /* is table an initialized module? */
        lua_pop(L, 1);
    else    /* no; initialize it */
    {
        lua_pop(L, 1);
        modinit(L, modname);
    }
    lua_pushvalue(L, -1);
    setfenv(L);
    dooptions(L, loaded - 1);
    return 0;
}


static int ll_seeall(lua_State *L)
{
    luaL_checktype(L, 1, LUA_TTABLE);
    if (!lua_getmetatable(L, 1))
    {
        lua_createtable(L, 0, 1); /* create new metatable */
        lua_pushvalue(L, -1);
        lua_setmetatable(L, 1);
    }
    lua_pushvalue(L, LUA_GLOBALSINDEX);
    lua_setfield(L, -2, "__index");  /* mt.__index = _G */
    return 0;
}


/* }====================================================== */



/* auxiliary mark (for internal use) */
#define AUXMARK     "\1"

static void setpath(lua_State *L, const char *fieldname, const char *envname,
                    const char *def)
{
    const char *path = getenv(envname);
    if (path == NULL)  /* no environment variable? */
        lua_pushstring(L, def);  /* use default */
    else
    {
        /* replace ";;" by ";AUXMARK;" and then AUXMARK by default path */
        path = luaL_gsub(L, path, LUA_PATHSEP LUA_PATHSEP,
                         LUA_PATHSEP AUXMARK LUA_PATHSEP);
        luaL_gsub(L, path, AUXMARK, def);
        lua_remove(L, -2);
    }
    setprogdir(L);
    lua_setfield(L, -2, fieldname);
}


static const luaL_Reg pk_funcs[] =
{
    {"loadlib", ll_loadlib},
    {"seeall", ll_seeall},
    {NULL, NULL}
};


static const luaL_Reg ll_funcs[] =
{
    {"module", ll_module},
    {"require", ll_require},
    {NULL, NULL}
};


static const lua_CFunction loaders[] =
{loader_preload, loader_Lua, loader_C, loader_Croot, NULL};

#if LUA_OPTIMIZE_MEMORY > 0
const luaR_entry lmt[] =
{
    {LRO_STRKEY("__gc"), LRO_FUNCVAL(gctm)},
    {LRO_NILKEY, LRO_NILVAL}
};
#endif

LUALIB_API int luaopen_package(lua_State *L)
{
    int i;
    /* create new type _LOADLIB */
#if LUA_OPTIMIZE_MEMORY == 0
    luaL_newmetatable(L, "_LOADLIB");
    lua_pushlightfunction(L, gctm);
    lua_setfield(L, -2, "__gc");
#else
    luaL_rometatable(L, "_LOADLIB", (void *)lmt);
#endif
    /* create `package' table */
    luaL_register_light(L, LUA_LOADLIBNAME, pk_funcs);
#if defined(LUA_COMPAT_LOADLIB)
    lua_getfield(L, -1, "loadlib");
    lua_setfield(L, LUA_GLOBALSINDEX, "loadlib");
#endif
    lua_pushvalue(L, -1);
    lua_replace(L, LUA_ENVIRONINDEX);
    /* create `loaders' table */
    lua_createtable(L, sizeof(loaders) / sizeof(loaders[0]) - 1, 0);
    /* fill it with pre-defined loaders */
    for (i = 0; loaders[i] != NULL; i++)
    {
        lua_pushcfunction(L, loaders[i]);
        lua_rawseti(L, -2, i + 1);
    }
    lua_setfield(L, -2, "loaders");  /* put it in field `loaders' */
    setpath(L, "path", LUA_PATH, LUA_PATH_DEFAULT);  /* set field `path' */
    setpath(L, "cpath", LUA_CPATH, LUA_CPATH_DEFAULT); /* set field `cpath' */
    /* store config information */
    lua_pushliteral(L, LUA_DIRSEP "\n" LUA_PATHSEP "\n" LUA_PATH_MARK "\n"
                    LUA_EXECDIR "\n" LUA_IGMARK);
    lua_setfield(L, -2, "config");
    /* set field `loaded' */
    luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 2);
    lua_setfield(L, -2, "loaded");
    /* set field `preload' */
    lua_newtable(L);
    lua_setfield(L, -2, "preload");
    lua_pushvalue(L, LUA_GLOBALSINDEX);
    luaL_register(L, NULL, ll_funcs);  /* open lib into global table */
    lua_pop(L, 1);
    return 1;  /* return 'package' table */
}

